The present invention relates to a centralized computing architecture using a broadband home signal distribution system for transmitting data and video display signals between a plurality of communications stations, for instance personal computers and video display devices.
Broadband video distribution systems are widely employed by cable television (hereinafter xe2x80x9cCATVxe2x80x9d) system operators for providing cable television services. These systems distribute cable television signals to residential and commercial subscribers. A broadband television signal is broadcast from a cable system head-end location over a coaxial cable or hybrid fiber coaxial (hereinafter xe2x80x9cHFCxe2x80x9d) cable network to subscriber households or commercial locations. The cable system headend is the local originating point for broadcast signals which are transmitted over the coaxial cable or HFC network. The broadband distribution system is terminated at the subscriber site with a connection to a home coaxial cable signal distribution network.
In general, CATV signals are transmitted in parallel over the coaxial cable or HFC network using frequency division multiplexing, where each of multiple video channels is frequency modulated to a unique non-overlapping frequency and combined onto the shared radio frequency (hereinafter xe2x80x9cRFxe2x80x9d) medium. Each of the video channels remains independent of one another when transmitted (i.e., they do not interfere with each other because of their non-overlapping frequency assignments.) CATV signals typically use a downstream frequency having a range of from about 50 MHz to about 550 MHz for broadcast transmission. Recently, many CATV systems have been upgraded to support a higher frequency transmission, for example, up to 860 MHz or 1 GHz. In some CATV systems, the upgrade results in the replacement of coaxial cables in the system backbone with fiber optic transmission media.
The broadband cable distribution system typically includes a carrier medium, for instance, a coaxial cable or fiber optics cable, to transmit broadband video signals within the downstream frequency range from the cable headend to the subscriber. However, because a broadband signal can become reduced in energy as it travels along the coaxial cable over long distances, or when the broadband signal is split for distribution to remote locations, amplifiers (or fiber optic nodes) may be spaced periodically along the cable distribution system to regenerate the broadband signal. A cable distribution system which supports two-way communication may also include a return band. A return band is usually designed to carry signals, generated at a subscriber location, in a frequency range of from about 5 MHz to about 42 MHz. Such signals may be transmitted in a reverse direction along the return band toward the cable system headend location. These reverse signals are generally diverse and have historically been used to transmit information, such as pay-per-view event purchases, from a subscriber location back to the headend location.
Recent advances have also permitted efficient and cost effective delivery of voice telephony, highspeed data communications, and interactive video services over the broadband cable distribution system, between a subscriber location and the cable headend location. These new services have been made compatible with existing services by using frequency division multiplexing, which allows each new channel or each new cable service to remain independent of the other signals or services present on the coaxial cable network. Moreover, similar to existing video services, these new services focus on the delivery to the home or between the home and the cable system headend location using the existing signal distribution system and methods. Existing signal delivery services, as well as emerging ones, typically employ signal receiving and processing equipment, such as a settop box or a cable modem. A settop or a cable modem is used to first terminate and process communication signals from the cable distribution network and thereafter forward the signals to an appropriate home appliance, such as a TV, personal computer, or telephone.
In addition to a settop box, an existing in-home coaxial cable wiring system may also be used to connect the cable distribution system to devices within the home that receive, use, display, and interact with cable services. This in-home coaxial cable wiring system is often in a star or a tree and branch topology, and includes coaxial cable wiring, passive electrical splitters, and other additional components. Currently, the in-home coaxial cable wiring is only partially utilized as a resource for enabling activities such as an in-home multimedia computing and entertainment. To better utilize the in-home coaxial cable wiring, recently developed methods and systems seek to make use of the in-home coaxial cable wiring or a similar coaxial cable wiring configuration to create, for example, a broadband local area network (hereinafter xe2x80x9cLANxe2x80x9d), multimedia network, or home automation system.
U.S. Pat. No. 4,893,326 to Duran discloses a video-telephone communication system in which audio and video signals are transmitted over a coaxial cable network between workstations and audio/video equipment. The Duran system employs a cable distribution unit to perform frequency translation and signal amplification for reduction of video signal ghosting. Duran also discloses using a dual-cable system, instead of a cable distribution unit, to enable this system without frequency translation. The Duran system, however, requires significant circuitry, electronic components, and installation of a cable distribution unit in order to work with existing home coaxial wiring schemes. Alternatively, a second coaxial cable must be installed to each terminating appliance to make this system operational in existing homes.
U.S. Pat. No. 5,534,914 to Flohr discloses a video conferencing system in which data and video signals are transmitted over a coaxial cable network between digital computer workstations and audio/video equipment. The Flohr system employs decentralized computing for the purpose of video conferencing. In other words, each workstation contains a processor and intelligence for selecting the appropriate frequency for signal transmission, reception, and processing. No centralized computing or processing is disclosed, nor are any derivative entertainment applications suggested for the Flohr system. The Flohr system uses an active electronic tuner to select an existing broadband video channel for transmission over the proposed coaxial cable network, where external signals, such as those from a cable television service, are to be transmitted in the video conferencing system. This configuration is not compatible with existing cable television services, which require that a complete broadband signal be present at each terminating home appliance, such as a television monitor, for tuning and possibly descrambling the entire range of cable television channels. Reconfiguration of the Flohr system for compatibility with existing cable television services may not be cost effective.
U.S. Pat. No. 4,935,924 to Baxter discloses a signal distribution network for transmitting video and other signals over a coaxial cable network between a plurality of signal sources and a plurality of signal receivers. A single channel allocation controller is connected on the coaxial cable and is used to transmit channel selection signals on the cable to both the sources and receivers. The employment of active electronics in the controller requires significant component and installation expense. The Baxter system also employs two cable sections, a downstream section and an upstream section, to each terminating appliance. The need for a second coaxial cable section in a home environment where only one coaxial cable currently exists can be costly.
U.S. Pat. No. 5,539,880 to Lakhani discloses a cable-based interactive multimedia workstation network using coaxial cable in a loop topology for connecting multimedia workstations and enabling full motion picture transmission, high fidelity audio communications, and data transmission. The loop topology, however, cannot be used for existing home coaxial cable systems without significant rewiring expense. The current home coaxial cable system uses a star or tree and branch topology.
U.S. Pat. No. 5,485,630 to Lee discloses an audio/video distribution system using coaxial cable for connecting signals between home appliances and workstations. In the Lee system, one element of the Consumer Electronic Bus (hereinafter xe2x80x9cCEBusxe2x80x9d) Standard requires the use of an active electronic device at Node 0 in the home. This active electronic device provides block conversion (frequency shifting) to avoid in-home communications signals from interfering with existing cable television or off-air video services. The Lee system utilizes a dual coaxial cable configuration. The deployment of a second coaxial cable and active electronics at Node 0 into existing home coaxial wiring schemes can be costly.
U.S. Pat. No. 5,491,508 to Friedell discloses a PC video conferencing system, wherein coaxial cables are used to connect a plurality of computer workstations to one another via a communication hub. The Friedell system, which does not employ centralized computing for multimedia and entertainment purposes, utilizes an active electronic hub device for channel selection and modulation. The Friedell system, in addition, employs a dual coaxial cable in a star topology. To adapt the Friedell system to current home coaxial wiring schemes is costly.
U.S. Pat. No. 5,579,308 to Humpleman discloses a home network architecture using a crossbar/hub arrangement for multimedia network to connect a home computer with entertainment devices. While Humpleman establishes an in-home network, the system requires active electronic components in the network interface unit to selectively connect in-home devices to the broadband network. The need for a network interface unit and the cost associated with its installation can increase the expense significantly if the Humpleman system is used for the creation of an in-home network using existing coaxial cable wiring.
There are also systems to provide in-home monitoring using remote cameras that display image information on a television monitor using the home coaxial cable wiring system. One such example is U.S. Pat. RE 34,895 to Morotomi which discloses a home automation system. Morotomi discloses means for using remote cameras and in-home coaxial cable wiring for monitoring. Morotomi also discloses the use of a home bus, but does not provide any specific detail regarding the home bus. In addition, no disclosure is made regarding the potential interference between the remote camera video signals and the broadband video signals during simultaneous use of monitoring and video reception or during simultaneous reception of video signals on multiple television sets within a home. It should be noted that a typical splitter device used in an existing in-home coaxial wiring scheme provides from about 20 dB to about 40 dB of isolation between the output ports to minimize the interference with the broadcast video signal and minimize the ghosting caused by signal reflections. However, the present isolation capability of splitter devices in existing coaxial wiring schemes, which is being used to increase the quality of broadcast video signals, may prevent, in some instances, an adequate signal strength from reaching receiving devices of an RF home broad-band system, unless additional signal strength is provided at a transmitter to overcome the splitter isolation. If additional signal strength is used (usually at additional expenses) to overcome the splitter isolation, increased output filtering is required (also at a significant expense) to prevent interference with existing video services. Furthermore, locally transmitted signals of high strength are more likely to interfere with reception of broadcast video services. Moreover, the use of remote cameras, such as those disclosed in the Morotomi, may cause remote camera signals that are transmitted back onto the cable distribution system to interfere with existing cable television services on the cable operator distribution system. The Morotomi and similar systems also do not utilize a centralized computing design. Rather, dedicated computers are employed, at significant additional expense, at each receiving device (e.g., a television monitor or video monitor) to receive and appropriately process and display remote images.
Accordingly, it is desirable to provide a cost effective system for providing a centralized computing network for transmitting data and video display signals between a plurality of communications stations, such as a television, video monitors or emerging digital TV display devices, over existing home coaxial cable wiring schemes without the employment of costly dedicated and proprietary devices.
The present invention makes unique use of new and existing in-home coaxial wiring systems to provide centralized computing with remote input of data from a communications station and remote display of the processed results to the appropriate display monitor associated with the communications station within a residential home. In general, current systems utilizing in-home wiring schemes for remote computing and entertainment employ a decentralized set up. These decentralized systems must be set up so that any end-point (i.e., terminating communications station) may communicate with any other end-points by going through a processing unit to which each end-point is connected, or by going through a cable connecting each of the end-points to one another. The system of the present invention, on the other hand, is a centralized system generally having a central processing unit. The system is designed to allow communication between the processing unit and those end-points having a pathway to the processing unit, but not necessarily between end-points directly.
In accordance with one embodiment of the present invention, a system is provided for permitting an interface between a central computing apparatus, for example, a computer, and at least one remotely situated communications station, for instance, a keyboard and associated television monitor and associated keyboard. The interface system, in a preferred embodiment, includes a two-way signal path, such as an in-home coaxial cable, for facilitating communication between the communications station and the central computing apparatus. The signal path is coupled to an external signal distribution system, for example, a subscriber drop circuit to the subscriber home if the external distribution system is CATV. If, on the other hand, the external signal distribution system is for satellite TV, the signal path will be, of course, connected to a satellite signal receiver rather than a CATV drop cable. In general, the CATV cable distribution system is designed to transmit and receive signals below a frequency band f1. Where the external CATV cable system intersects the signal path, a frequency sensitive splitter/reflector device is employed for reflecting input signals, generated above the frequency band f1 from the communications station, and output signals, also generated above the frequency band f1 from the central computing apparatus, along the signal path between the communications station and the central computing apparatus. The splitter/reflector, however, allows signals from the CATV cable system below the frequency band f1 to be freely transmitted onto the in-home signal path, and move along the path to and from a terminating communications station, for instance, a settop box or a computer. In this manner, interference between the signals from the CATV cable system and signals generated from the central computing apparatus and communications station, can be minimized along the signal path. Furthermore, the frequency sensitive nature of the splitter/reflector device protects signals passing between the centralized computing apparatus and communications station from being forwarded, as interference, onto the CATV cable distribution system. The splitter/reflector device also prevents a frequency band below f1 from passing between the centralized computing apparatus and communications station to prevent ghosting and interference caused by reflection of signals having a frequency band below f1.
The present system also includes a first component and a fourth component positioned in the signal path adjacent and the central computing apparatus for providing an interface between the computing apparatus and the communications station. The first component is designed to modulate output signals from the central computing apparatus to a frequency band f2, and to convert the output signals to a format compatible for detection and display by the communications station. The fourth component is designed to demodulate input signals from the communications station to a digital baseband signal recognizable by the central computing apparatus, and for converting the input signals from the communications station to a format compatible for processing by the central computing apparatus.
The system further includes a second component and a third component positioned in the signal path adjacent and each communications station for providing an interface between the computing apparatus and the communications station. The second component is designed to frequency shift or demodulate the output signals from the central computing apparatus to a frequency or baseband signal receivable by the communications station, and to format, if necessary, the converted output signals from the central computing apparatus for detection by the communications station. The third component is designed to modulate the input signals from the communications station to a frequency band f3, and for transmitting the input signals to the central computing apparatus. Input signals may be generated by one or multiple standard computer input devices, including but not limited to a keyboard, mouse device, digital or analog video camera, audio microphone, etc. It should be appreciated that frequency bands f2 and f3 are not similar to frequency band f1, and are generally greater than frequency band f1. Transmission of frequency bands f2 and f3 are limited to transmission along the signal path by the reflector.
The interface system of the present invention may be used to provide a system for enabling multimedia computing and entertainment, including but not limited to reception of digital television or broadband media, audio/video conferencing, accessing the World Wide Web (hereinafter xe2x80x9cWWWxe2x80x9d), and playing interactive games, over existing home coaxial cable wiring schemes using, for instance, remote input devices and associated television monitors, video display monitors, or emerging digital display apparatuses, in connection with a personal computer. Moreover, the design of the present interface system permits remote use of a personal computer in a centralized manner, thereby enabling multiple shared uses for this computer from remote locations, in addition to dedicated computing. Shared use of a centralized computing apparatus is more cost effective than employment of these apparatuses in a dedicated manner. The present interface system also permits frequency sensitive network partitioning of a coaxial cable wiring system in residential homes, using only passive electronic devices at key coaxial cable intersections in the home to minimize component and installation cost. This may be achieved while providing the present interface system with compatibility to existing and emerging broadcast TV, CATV, telephony, and high-speed data services provided over a cable distribution system. In other words, the present system does not interfere with services external to the residential home, such as those provided over an external coaxial cable or HFC distribution system.
The centralized computing design of the present system further permits an increase in the processing power, memory, and video display capabilities of remotely situated communications stations, for example, television monitors, such that these remotely situated communications stations may be provided with interactive multimedia computing and entertainment. The present interface system may be utilized with minimal installation and operating expenses typically associated with the connection of a computer to each remote television monitor, monitor display, or emerging digital display apparatus and input device.